Preventive medicine programs for armies, from antiquity to the present, have been designed and operated to prevent physical and mental diseases and disabilities, and to preserve and promote health among all personnel essential to the military effort. With varying degrees of potential efficacy, conditioned by the state of knowledge and by the enterprise of leaders and their followers, these programs have provided for the application of measures of control not only in strictly military situations but also in civilian populations in the environment of war areas when conditions in such groups were threats to the health of troops or possible hindrances to the progress of campaigns. These programs have been and must be, intelligent combinations of measures which rest upon the responsibility of the individual person and of public health activities which are the responsibility of the community.